| dc.description |
A series of new alkyl N,N-disubstituted 2-aminothiazole-5-carboxylates was prepared by condensing α-bromo-β-oxo-esters with N,N-disubstituted thioureas. The products exhibit i.r. carbonyl doublets, the higher and lower wavenumber components arising from the carbonyl O,S-syn-s-trans and anti-s-trans rotamers respectively. Variable temperature <sup>1</sup>H n.m.r. examination showed that the barriers to rotation of the 2-amino-groups are in the range 41â 47 kJ mol<sup>â 1</sup>. Further evidence for rotational isomerism of the carboxylate group was provided by <sup>13</sup>C n.m.r. study, but the size of its rotational barrier could not be assessed.The spectrometric work shows that there is strong mesomeric interaction between the carboxylate and amine groups. |
